Image sensor device

ABSTRACT

An image sensor device is provided. The image sensor device includes a semiconductor substrate including a front surface, a back surface opposite to the front surface, and a light-sensing region extending from the front surface into the semiconductor substrate. The image sensor device includes a light-blocking structure in the semiconductor substrate and surrounding the light-sensing region. The light-blocking structure includes a conductive light reflection structure and a light absorption structure, and the light absorption structure is between the conductive light reflection structure and the back surface. The image sensor device includes an insulating layer between the light-blocking structure and the semiconductor substrate.

CROSS REFERENCE

This application is a Divisional of U.S. application Ser. No.14/192,258, filed on Feb. 27, 2014, the entirety of which isincorporated by reference herein.

BACKGROUND

The semiconductor integrated circuit (IC) industry has experienced rapidgrowth. Technological advances in IC materials and design have producedgenerations of ICs where each generation has smaller and more complexcircuits than the previous generation. In the course of IC evolution,functional density (i.e., the number of interconnected devices per chiparea) has generally increased while geometric size (i.e., the smallestcomponent that can be created using a fabrication process) hasdecreased. Such advances have increased the complexity of processing andmanufacturing ICs. For these advances, similar developments in ICprocessing and manufacturing are needed.

Along with the advantages realized from reducing geometry size,improvements are being made directly to the IC devices. One such ICdevice is an image sensor device. An image sensor device includes apixel array (or grid) for detecting light and recording intensity(brightness) of the detected light. The pixel array responds to thelight by accumulating a charge. The higher the intensity of the lightis, the more the charge is accumulated in the pixel array. Theaccumulated charge is then used (for example, by other circuitry) toprovide image information for use in a suitable application, such as adigital camera.

However, since the feature sizes continue to decrease, fabricationprocesses continue to become more difficult to perform. Therefore, it isa challenge to form reliable image sensor devices with smaller andsmaller sizes.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIGS. 1A-1D are cross-sectional views of various stages of a process forforming an image sensor device, in accordance with some embodiments.

FIGS. 2A-2C are cross-sectional views of various stages of a process forforming an image sensor device, in accordance with some embodiments.

FIGS. 3A-3D are cross-sectional views of various stages of a process forforming an image sensor device, in accordance with some embodiments.

FIGS. 4A-4D are cross-sectional views of various stages of a process forforming an image sensor device, in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly. It is understood thatadditional operations can be provided before, during, and after themethod, and some of the operations described can be replaced oreliminated for other embodiments of the method.

FIGS. 1A-1D are cross-sectional views of various stages of a process forforming an image sensor device 100, in accordance with some embodiments.As shown in FIG. 1A, a semiconductor substrate 110 is provided. Thesemiconductor substrate 110 has a front surface 112 and a back surface114 opposite to the front surface 112.

The semiconductor substrate 110 may be a silicon substrate doped with aP-type dopant such as boron, in which case the semiconductor substrate110 is a P-type substrate. Alternatively, the semiconductor substrate110 could be another suitable semiconductor material. For example, thesemiconductor substrate 110 may be a silicon substrate doped with anN-type dopant such as phosphorous or arsenic, in which case thesubstrate is an N-type substrate. The semiconductor substrate 110 mayinclude other elementary semiconductor materials such as germanium.

In some embodiments, isolation structures 120 are formed in thesemiconductor substrate 110 to define various light-sensing regions inthe semiconductor substrate 110, and to electrically isolate neighboringdevices (e.g. transistors) from one another. In some embodiments, theisolation features 120 are formed adjacent to or near the front surface112.

In some embodiments, the isolation structures 120 are made of adielectric material, such as silicon oxide, silicon nitride, siliconoxynitride, fluoride-doped silicate glass (FSG), a low-K dielectricmaterial, other suitable materials, or combinations thereof. In someembodiments, the isolation structures 120 are formed by using anisolation technology, such as local oxidation of semiconductor (LOCOS),shallow trench isolation (STI), or the like.

In some embodiments, the formation of the isolation structures 120includes patterning the semiconductor substrate 110 by aphotolithography process, etching trenches in the semiconductorsubstrate 110 (for example, by using a dry etching, wet etching, plasmaetching process, or combinations thereof), and filling the trenches (forexample, by using a chemical vapor deposition process) with thedielectric material. In some embodiments, the filled trenches may have amulti-layer structure, such as a thermal oxide liner layer filled withsilicon nitride or silicon oxide.

In some embodiments, the semiconductor substrate 110 is fabricated withfront end processes, in accordance with some embodiments. For example,the semiconductor substrate 110 includes various regions, which mayinclude a pixel region, a periphery region, a bonding pad region, and ascribe line region. For the sake of simplicity, only a portion of thepixel region is shown in FIGS. 1 to 4.

The pixel region includes pixels each with a light-sensing region 116(also referred to as a radiation-sensing region). The light-sensingregions 116 of the pixels are doped with a doping polarity opposite fromthat of the semiconductor substrate 110. The light-sensing regions 116are formed by one or more implantation processes or diffusion processes.The light-sensing regions 116 are formed close to (or adjacent to, ornear) the front surface 112 of the semiconductor substrate 110. Thelight-sensing regions 116 are operable to sense incident light (orincident radiation) that enters the pixel region. The incident light maybe visible light. Alternatively, the incident light may be infrared(IR), ultraviolet (UV), X-ray, microwave, other suitable types of light,or a combination thereof.

Although only a portion of the pixel region is shown in FIGS. 1A-1D, thepixel region may further include pinned layers, photodiode gates, resettransistors, source follower transistors, and transfer transistors. Thetransfer transistors are electrically connected with the light-sensingregions 116 to collect (or pick up) electrons generated by incidentlight (incident radiation) traveling into the light-sensing regions 116and to convert the electrons into voltage signals, in accordance withsome embodiments. For the sake of simplicity, detailed structures of theabove features are not shown in figures of the present disclosure.

In some embodiments, an interconnection structure 130 is formed over thefront surface 112. The interconnection structure 130 includes a numberof patterned dielectric layers and conductive layers that couple tovarious doped features, circuitry, photodiode gates, reset transistors,source follower transistors, and transfer transistors. For example, theinterconnection structure 130 includes an interlayer dielectric (ILD)layer 132 and a multilayer interconnection (MLI) structure 134 in theILD layer 132.

The MLI structure 134 includes conductive lines 134 a and vias (orcontacts) 134 b connected between the conductive lines 134 a. It shouldbe understood that the conductive lines 134 a and the vias 134 b aremerely exemplary. The actual positioning and configuration of theconductive lines 134 a and the vias 134 b may vary depending on designneeds and manufacturing concerns.

Afterwards, a carrier substrate 140 is bonded with the interconnectionstructure 130, in accordance with some embodiments. The carriersubstrate 140 includes a silicon substrate, a glass substrate or anothersuitable substrate. Thereafter, as shown in FIGS. 1A and 1B, a thinningprocess is performed to thin the semiconductor substrate 110 from theback surface 114. The thinning process may include a chemical mechanicalpolishing process.

Afterwards, the semiconductor substrate 110 is flipped over, and deeptrenches 118 are formed in the semiconductor substrate 110, inaccordance with some embodiments. The deep trenches 118 extend from theback surface 114, in accordance with some embodiments. The deep trenches118 are between the light-sensing regions 116, in accordance with someembodiments. In some embodiments, the deep trenches 118 are above theisolation structures 120, respectively. In some embodiments, a ratio ofa depth D1 of the deep trenches 118 to a thickness T1 of thesemiconductor substrate 110 ranges from about 10% to about 100%. In someembodiments, the ratio of the depth D1 of the deep trenches 118 to thethickness T1 of the semiconductor substrate 110 ranges from about 50% toabout 100%.

Afterwards, an insulating layer 150 (also referred to as a liner layer)is formed on the back surface 114 of the semiconductor substrate 110,bottom surfaces and inner walls of the deep trenches 118, in accordancewith some embodiments. In some embodiments, the insulating layer 150 isconfigured to passivate the back surface 114 of the semiconductorsubstrate 110, the bottom surfaces and the inner walls of the deeptrenches 118. In some embodiments, the insulating layer 150 is alsoconfigured to electrically isolate the light-sensing regions 116 fromone another to reduce electrical crosstalk between the light-sensingregions 116. The insulating layer 150 includes silicon oxides or othersuitable insulating materials. The insulating layer 150 is formed by,for example, a thermal oxidation process.

Thereafter, as shown in FIG. 1C, light-blocking structures 160 areformed in the deep trenches 118, respectively. The deep trenches 118 arefilled with the light-blocking structures 160, in accordance with someembodiments. The light-blocking structures 160 are between thelight-sensing regions 116, in accordance with some embodiments. Thelight-blocking structures 160 are configured to block incident light toprevent the incident light from traveling between differentlight-sensing regions 116, in accordance with some embodiments.

In some embodiments, the light-blocking structures 160 include lightabsorption structures. In some embodiments, the light absorptionstructures have a light absorptivity ranging from about 60% to about100%. In some embodiments, the light absorption structures areconfigured to absorb the incident light arriving at the light absorptionstructures to prevent the incident light from traveling betweendifferent light-sensing regions 116.

In some embodiments, the light absorption structures include a blacksilicon material, a semiconductor material with a band gap smaller than1.5 eV (e.g., Ge, InSb, or InAs), or a polymer material (e.g., an opaquepolymer material). In some embodiments, the light absorption structuresinclude a non-visible light filter (e.g. an IR filter or a UV filter)enabled to block visible light and transmit non-visible light.

Alternatively, in some embodiments, the light-blocking structures 160include light reflection structures. In some embodiments, the lightreflection structures have a refractive index lower than that of thesemiconductor substrate 110, and therefore a portion of the incidentlight arriving at the light reflection structures is reflected, which isa phenomenon called “total internal reflection”. The light reflectionstructures include dielectric materials, such as silicon oxides, siliconnitrides, or silicon carbides.

In some embodiments, light reflection structures have a lightreflectivity ranging from about 60% to about 100%. In some embodiments,the light reflection structures include a metal material or an alloymaterial. The light reflection structures include Al, W, Cu, Ti, alloysthereof, combinations thereof, or other suitable reflective materials.

In some embodiments, the method of forming the light-blocking structures160 includes depositing a light-blocking material layer on thesemiconductor substrate 110 and filled in the deep trenches 118; andremoving the light-blocking material layer outside of the deep trenches118. The method of depositing the light-blocking material layer includesperforming a chemical vapor deposition (CVD) process, a physical vapordeposition (PVD) process, a coating process or another suitable process.The method of removing the light-blocking material layer outside of thedeep trenches 118 includes performing a chemical mechanical polishing(CMP) process or another suitable process.

Thereafter, an anti-reflection coating (ARC) layer 170 and a bufferlayer 180 are sequentially formed over the back surface 114 of thesemiconductor substrate 110, in accordance with some embodiments. TheARC layer 170 is used to reduce optical reflection from the back surface114 of the semiconductor substrate 110 to ensure that most of anincident light enters the light-sensing regions 116 and is sensed.

The ARC layer 170 may be made of a high-k material, a dielectricmaterial, other applicable materials, or a combination thereof. Thehigh-k material may include hafnium oxide, tantalum pentoxide, zirconiumdioxide, aluminum oxide, other suitable materials, or a combinationthereof. The dielectric material includes, for example, silicon nitride,silicon oxynitride, other suitable materials, or a combination thereof.

The buffer layer 180 is used as a buffer between the ARC layer 170 andan overlying layer subsequently formed. The buffer layer 180 may be madeof a dielectric material or other suitable materials. For example, thebuffer layer 180 is made of silicon oxide, silicon nitride, siliconoxynitride, other applicable materials, or a combination thereof.

Thereafter, a reflective grid 190 is formed over the buffer layer 180,in accordance with some embodiments. The reflective grid 190 may includereflective elements 192. In some embodiments, the reflective elements192 are aligned with the light-blocking structures 160, respectively.Each of the reflective elements 192 is used to prevent the incidentlight from entering a neighboring pixel. The crosstalk problems betweenpixels are thus prevented or reduced.

In some embodiments, the reflective grid 190 is made of a reflectivematerial such as a metal material. The reflective grid 190 may be madeof aluminum, silver, copper, titanium, platinum, tungsten, tantalum,tantalum nitride, other suitable materials, or a combination thereof. Insome embodiments, the reflective grid 190 is formed over the bufferlayer 180 using a suitable process. The suitable process includes, forexample, a PVD process, an electroplating process, a CVD process, otherapplicable processes, or a combination thereof.

Afterwards, a dielectric layer 210 is formed over the buffer layer 180to cover the reflective grid 190, in accordance with some embodiments.The dielectric layer 210 may be made of silicon oxide, silicon nitride,silicon oxynitride, or other suitable materials. The dielectric layer210 is formed by a CVD process or another suitable process. Thedielectric layer 210 has multiple recesses 212R, 212G, and 212B.

Thereafter, visible light filters (such as color filters 220R, 220G, and220B) are formed in the recesses 212R, 212G, and 212B, respectively. Insome embodiments, the visible light filters may be used to filterthrough visible light. The color filters 220R, 220G, and 220B may beused to filter through a red wavelength band, a green wavelength band,and a blue wavelength band, respectively. In some embodiments, thelight-blocking structures 160 include a non-visible light filter (e.g.an IR filter or a UV filter) enabled to block the visible light passingthough the visible light filters.

Afterwards, lenses 230 are respectively formed over the color filters220R, 220G, and 220B, in accordance with some embodiments. The lenses230 are used to direct or focus the incident light. The lenses 230 mayinclude a microlens array. The lenses 230 may be made of a hightransmittance material. For example, the high transmittance materialincludes transparent polymer material (such as polymethylmethacrylate,PMMA), transparent ceramic material (such as glass), other applicablematerials, or a combination thereof. In this step, an image sensordevice 100 is substantially formed, in accordance with some embodiments.

As shown in FIG. 1D, an incident light L passing through the colorfilters 220R and arriving at the light-blocking structure 160 may beabsorbed or reflected by the light-blocking structure 160. Therefore,the light-blocking structure 160 may reduce optical crosstalk.

FIGS. 2A-2C are cross-sectional views of various stages of a process forforming an image sensor device 200, in accordance with some embodiments.As shown in FIG. 2A, after the step of FIG. 1B, light reflectionstructures 162 a are formed in the deep trenches 118, respectively. Eachof the light reflection structures 162 a is partially filled in thecorresponding deep trench 118. The materials of the light reflectionstructures 162 a are substantially similar to those of the lightreflection structures of the embodiments of FIGS. 1A-1D.

In some embodiments, the method of forming the light reflectionstructures 162 a includes depositing a light reflection material layeron the semiconductor substrate 110 and filled in the deep trenches 118;removing the light reflection material layer outside of the deeptrenches 118; and removing a portion of the light reflection materiallayer in the deep trenches 118.

The method of depositing the light reflection material layer includesperforming a chemical vapor deposition (CVD) process, a physical vapordeposition (PVD) process, a coating process or another suitable process.The method of removing the light reflection material layer outside ofthe deep trenches 118 includes performing a chemical mechanicalpolishing (CMP) process or another suitable process. The method ofremoving the portion of the light reflection material layer in the deeptrenches 118 includes performing a wet etching process, a dry etchingprocess or another suitable process.

Afterwards, as shown in FIG. 2B, light absorption structures 164 a areformed on the light reflection structures 162 a in the deep trenches118, respectively. In some embodiments, a ratio of a thickness T2 of thelight absorption structure 164 a to the depth D1 of the deep trench 118ranges from about 10% to about 30%. In some embodiments, a ratio of athickness T3 of the light reflection structure 162 a to the depth D1 ofthe deep trench 118 ranges from about 70% to about 90%.

The materials of the light absorption structures 164 a are substantiallysimilar to those of the light absorption structures of the embodimentsof FIGS. 1A-1D. In each of the deep trenches 118, the light reflectionstructure 162 a and the light absorption structure 164 a constitute alight-blocking structure 160 a.

In some embodiments, the method of forming the light absorptionstructures 164 a includes depositing a light absorption material layeron the semiconductor substrate 110 and filled in the deep trenches 118;and removing the light absorption material layer outside of the deeptrenches 118.

The method of depositing the light absorption material layer includesperforming a chemical vapor deposition (CVD) process, a physical vapordeposition (PVD) process, a coating process or another suitable process.The method of removing the light absorption material layer outside ofthe deep trenches 118 includes performing a chemical mechanicalpolishing (CMP) process or another suitable process.

As shown in FIG. 2C, an anti-reflection coating (ARC) layer 170, abuffer layer 180, a reflective grid 190, a dielectric layer 210, visiblelight filters (such as color filters 220R, 220G, and 220B), and lenses230 are sequentially formed over the back surface 114 of thesemiconductor substrate 110, in accordance with some embodiments. Inthis step, an image sensor device 200 is substantially formed, inaccordance with some embodiments. In some embodiments, the lightabsorption structures 164 a are positioned closer to the back surface114 than to the front surface 112, and the light reflection structures162 a are positioned closer to the front surface 112 than to the backsurface 114.

As shown in FIG. 2C, an incident light L1 passing through the colorfilters 220R and arriving at the light reflection structure 162 a isreflected by the light reflection structures 162 a, in accordance withsome embodiments. An incident light L2 passing through the color filters220G and arriving at the light absorption structure 164 a may beabsorbed by the light absorption structure 164 a, which prevents theincident light L2 from being reflected to an adjacent light-sensingregion 116. Therefore, the light-blocking structures 160 a composed ofthe light reflection structure 162 a and the light absorption structure164 a may reduce optical crosstalk.

FIGS. 3A-3D are cross-sectional views of various stages of a process forforming an image sensor device 300, in accordance with some embodiments.As shown in FIG. 3A, a semiconductor substrate 110 is provided. Thesemiconductor substrate 110 has a front surface 112 and a back surface114 opposite to the front surface 112.

Afterwards, deep trenches 118 a are formed in the semiconductorsubstrate 110 to define various light-sensing regions in thesemiconductor substrate 110, in accordance with some embodiments. Thedeep trenches 118 a extend from the front surface 112, in accordancewith some embodiments. Thereafter, an insulating layer 150 a is formedon the front surface 112 of the semiconductor substrate 110, bottomsurfaces and inner walls of the deep trenches 118 a, in accordance withsome embodiments. In some embodiments, the insulating layer 150 a isconfigured to electrically isolate light-sensing regions subsequentlyformed from one another to reduce electrical crosstalk between thelight-sensing regions.

As shown in FIG. 3B, light-blocking structures 160 b are formed in thedeep trenches 118 a, respectively. The deep trenches 118 a are filledwith the light-blocking structures 160 b, in accordance with someembodiments. In some embodiments, the light-blocking structures 160 binclude light absorption structures or light reflection structures.

In some embodiments, the method of forming the light-blocking structures160 b includes depositing a light-blocking material layer on the frontsurface 112 of the semiconductor substrate 110 and filled in the deeptrenches 118 a; and removing the light-blocking material layer outsideof the deep trenches 118 a. In some embodiments, the insulating layer150 a outside of the deep trenches 118 a is also removed during theremoving of the light-blocking material layer outside of the deeptrenches 118 a.

Afterwards, light-sensing regions 116 are formed in the semiconductorsubstrate 110 and between the deep trenches 118 a. The light-sensingregions 116 are formed by one or more implantation processes ordiffusion processes. The light-sensing regions 116 are formed close to(or adjacent to, or near) the front surface 112 of the semiconductorsubstrate 110.

As shown in FIG. 3C, an interconnection structure 130 is formed over thefront surface 112. The interconnection structure 130 includes a numberof patterned dielectric layers and conductive layers that couple tovarious doped features, circuitry, photodiode gates, reset transistors,source follower transistors, and transfer transistors.

For example, the interconnection structure 130 includes an interlayerdielectric (ILD) layer 132 and a multilayer interconnection (MLI)structure 134 in the ILD layer 132. The MLI structure 134 includesconductive lines 134 a and vias (or contacts) 134 b connected betweenthe conductive lines 134 a. Afterwards, a carrier substrate 140 isbonded with the interconnection structure 130, in accordance with someembodiments.

Thereafter, as shown in FIGS. 3C and 3D, a thinning process is performedto thin the semiconductor substrate 110 from the back surface 114.Afterwards, the semiconductor substrate 110 is flipped over. As shown inFIG. 3D, an anti-reflection coating (ARC) layer 170, a buffer layer 180,a reflective grid 190, a dielectric layer 210, visible light filters(such as color filters 220R, 220G, and 220B), and lenses 230 aresequentially formed over the back surface 114 of the semiconductorsubstrate 110, in accordance with some embodiments. In this step, animage sensor device 300 is substantially formed, in accordance with someembodiments.

FIGS. 4A-4D are cross-sectional views of various stages of a process forforming an image sensor device 400, in accordance with some embodiments.As shown in FIG. 4A, after the step of FIG. 3A, light absorptionstructures 164 b are formed in the deep trenches 118 a, respectively.Each of the light absorption structures 164 b is partially filled in thecorresponding deep trench 118 a. The materials of the light absorptionstructures 164 b are substantially similar to those of the lightabsorption structures of the embodiments of FIGS. 1A-1D.

In some embodiments, the method of forming the light absorptionstructures 164 b includes depositing a light absorption material layeron the semiconductor substrate 110 and filled in the deep trenches 118a; removing the light absorption material layer outside of the deeptrenches 118 a; and removing a portion of the light absorption materiallayer in the deep trenches 118 a. In some embodiments, the insulatinglayer 150 a outside of the deep trenches 118 a is also removed duringthe removal of the light absorption material layer outside of the deeptrenches 118 a.

The method of depositing the light absorption material layer includesperforming a CVD process, a PVD process, a coating process or anothersuitable process. The method of removing the light absorption materiallayer outside of the deep trenches 118 a includes performing a CMPprocess or another suitable process. The method of removing the portionof the light absorption material layer in the deep trenches 118 aincludes performing a wet etching process, a dry etching process oranother suitable process.

Afterwards, as shown in FIG. 4B, light reflection structures 162 b areformed on the light absorption structures 164 b in the deep trenches 118a, respectively. In some embodiments, a ratio of a thickness T4 of thelight absorption structure 164 b to the depth D1 of the deep trench 118a ranges from about 10% to about 30%. In some embodiments, a ratio of athickness T5 of the light reflection structure 162 b to the depth D1 ofthe deep trench 118 a ranges from about 70% to about 90%.

The materials of the light reflection structures 162 b are substantiallysimilar to that of the light reflection structures of the embodiments ofFIGS. 1A-1D. In each of the deep trenches 118 a, the light absorptionstructure 164 b and the light reflection structure 162 b constitute alight-blocking structure 160 b.

In some embodiments, the method of forming the light reflectionstructures 162 b includes depositing a light reflection material layeron the semiconductor substrate 110 and filled in the deep trenches 118a; and removing the light reflection material layer outside of the deeptrenches 118 a.

The method of depositing the light reflection material layer includesperforming a CVD process, a PVD process, a coating process or anothersuitable process. The method of removing the light reflection materiallayer outside of the deep trenches 118 a includes performing a CMPprocess or another suitable process. Afterwards, light-sensing regions116 are formed in the semiconductor substrate 110 and between the deeptrenches 118 a.

As shown in FIG. 4C, an interconnection structure 130 is formed over thefront surface 112. The interconnection structure 130 includes a numberof patterned dielectric layers and conductive layers that couple tovarious doped features, circuitry, photodiode gates, reset transistors,source follower transistors, and transfer transistors.

For example, the interconnection structure 130 includes an interlayerdielectric (ILD) layer 132 and a multilayer interconnection (MLI)structure 134 in the ILD layer 132. The MLI structure 134 includesconductive lines 134 a and vias (or contacts) 134 b connected betweenthe conductive lines 134 a. Afterwards, a carrier substrate 140 isbonded with the interconnection structure 130, in accordance with someembodiments.

Thereafter, as shown in FIGS. 4C and 4D, a thinning process is performedto thin the semiconductor substrate 110 from the back surface 114.Afterwards, the semiconductor substrate 110 is flipped over.

As shown in FIG. 4D, an anti-reflection coating (ARC) layer 170, abuffer layer 180, a reflective grid 190, a dielectric layer 210, visiblelight filters (such as color filters 220R, 220G, and 220B), and lenses230 are sequentially formed over the back surface 114 of thesemiconductor substrate 110, in accordance with some embodiments. Inthis step, an image sensor device 400 is substantially formed, inaccordance with some embodiments. In some embodiments, the lightabsorption structures 164 b are positioned closer to the back surface114 than to the front surface 112, and the light reflection structures162 b are positioned closer to the front surface 112 than to the backsurface 114.

As shown in FIG. 4D, an incident light L3 passing through the colorfilters 220R and arriving at the light reflection structure 162 b isreflected by the light reflection structures 162 b, in accordance withsome embodiments. An incident light L4 passing through the color filters220G and arriving at the light absorption structure 164 b may beabsorbed by the light absorption structure 164 b, which prevents theincident light L4 from being reflected to an adjacent light-sensingregion 116. Therefore, the light-blocking structures 160 b composed ofthe light reflection structure 162 b and the light absorption structure164 b may reduce optical crosstalk.

In accordance with some embodiments, image sensor devices and methodsfor forming the same are provided. The methods (for forming the imagesensor devices) form light-blocking structures in deep trenches betweenlight-sensing regions in a semiconductor substrate. The light-blockingstructures may block incident light arriving at the light-blockingstructures to prevent the incident light from traveling between thedifferent light-sensing regions. Therefore, optical crosstalk isreduced. Furthermore, the methods form an insulating layer in the deeptrenches to electrically isolate the light-sensing regions from oneanother, which reduces electrical crosstalk.

In accordance with some embodiments, an image sensor device is provided.The image sensor device includes a semiconductor substrate including afront surface, a back surface opposite to the front surface, and alight-sensing region extending from the front surface into thesemiconductor substrate. The image sensor device includes alight-blocking structure in the semiconductor substrate and adjacent tothe light-sensing region. The light-blocking structure includes aconductive light reflection structure and a light absorption structure,and the light absorption structure is between the conductive lightreflection structure and the back surface. The image sensor deviceincludes an insulating layer between the light-blocking structure andthe semiconductor substrate.

In accordance with some embodiments, an image sensor device is provided.The image sensor device includes a semiconductor substrate including afront surface, a back surface opposite to the front surface, and alight-sensing region extending from the front surface into thesemiconductor substrate. The image sensor device includes a conductivelight reflection structure penetrating into the semiconductor substratefrom the front surface and adjacent to the light-sensing region. Theconductive light reflection structure has an end surface facing the backsurface. The image sensor device includes a light absorption structurein the semiconductor substrate and between the end surface of theconductive light reflection structure and the back surface. The imagesensor device includes an insulating layer in the semiconductorsubstrate and adjacent to the conductive light reflection structure andthe light absorption structure to separate the conductive lightreflection structure and the light absorption structure from thesemiconductor substrate.

In accordance with some embodiments, an image sensor device is provided.The image sensor device includes a semiconductor substrate including afront surface, a back surface opposite to the front surface, and alight-sensing region extending from the front surface into thesemiconductor substrate. The image sensor device includes a conductivelight reflection structure penetrating into the semiconductor substratefrom the front surface. The conductive light reflection structure isadjacent to the light-sensing region. The image sensor device includes alight absorption structure in the semiconductor substrate and betweenthe conductive light reflection structure and the back surface, whereina first sidewall of the conductive light reflection structure and asecond sidewall of the light absorption structure are substantiallycoplanar. The image sensor device includes an insulating layer in thesemiconductor substrate and adjacent to the conductive light reflectionstructure and the light absorption structure to separate the conductivelight reflection structure and the light absorption structure from thesemiconductor substrate.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. An image sensor device, comprising: asemiconductor substrate comprising a front surface, a back surfaceopposite to the front surface, and a light-sensing region extending fromthe front surface into the semiconductor substrate; a light-blockingstructure in the semiconductor substrate and adjacent to thelight-sensing region, wherein the light-blocking structure comprises aconductive light reflection structure and a light absorption structure,the light absorption structure is between the conductive lightreflection structure and the back surface, the conductive lightreflection structure has a light reflectivity ranging from 60% to 100%,the light absorption structure has a light absorptivity ranging from 60%to 100%, the light absorption structure is in direct contact with theconductive light reflection structure, and a boundary is between thelight absorption structure and the conductive light reflection structureand extends toward the light-sensing region; an insulating layer betweenthe light-blocking structure and the semiconductor substrate, whereinthe insulating layer conformally covers a first sidewall of the lightabsorption structure and a second sidewall of the conductive lightreflection structure, and the boundary extends to the insulating layer;and a lens over the back surface and covering the light-sensing region.2. The image sensor device as claimed in claim 1, wherein a first topsurface of the conductive light reflection structure, a second topsurface of the insulating layer, and the front surface are substantiallycoplanar.
 3. The image sensor device as claimed in claim 1, wherein thelight absorption structure comprises a black silicon material, and theinsulating layer separates the light absorption structure from thesemiconductor substrate to electrically isolate the light absorptionstructure from the semiconductor substrate.
 4. The image sensor deviceas claimed in claim 1, wherein the conductive light reflection structurecomprises a metal material or an alloy material.
 5. The image sensordevice as claimed in claim 1, wherein the semiconductor substrate ispartially between the light absorption structure and the back surface.6. The image sensor device as claimed in claim 1, further comprising: ananti-reflection coating layer over the back surface of the semiconductorsubstrate; a buffer layer over the anti-reflection coating layer andcovering the light-sensing region; and a reflective grid over the bufferlayer, wherein the reflective grid comprises at least one reflectiveelement, and the light absorption structure is between the at least onereflective element and the conductive light reflection structure.
 7. Theimage sensor device as claimed in claim 6, wherein a first width of theat least one reflective element is greater than both of a second widthof the conductive light reflection structure and a third width of thelight absorption structure.
 8. An image sensor device, comprising: asemiconductor substrate comprising a front surface, a back surfaceopposite to the front surface, and a light-sensing region extending fromthe front surface into the semiconductor substrate; a conductive lightreflection structure penetrating into the semiconductor substrate fromthe front surface and adjacent to the light-sensing region, wherein theconductive light reflection structure has an end surface facing the backsurface; a light absorption structure in the semiconductor substrate andbetween the end surface of the conductive light reflection structure andthe back surface, wherein the light absorption structure is thinner thanthe conductive light reflection structure in a direction perpendicularto the back surface, the light absorption structure has a higher lightabsorptivity than the conductive light reflection structure, theconductive light reflection structure has a higher light reflectivitythan the light absorption structure, and the conductive light reflectionstructure is in direct contact with the light absorption structure; andan insulating layer in the semiconductor substrate and conformallycovering the conductive light reflection structure and the lightabsorption structure to separate the conductive light reflectionstructure and the light absorption structure from the semiconductorsubstrate, wherein a boundary between the conductive light reflectionstructure and the light absorption structure straightly extends towardthe light-sensing region and ends at the insulating layer.
 9. The imagesensor device as claimed in claim 8, wherein the conductive lightreflection structure is in direct contact with the light absorptionstructure.
 10. The image sensor device as claimed in claim 8, furthercomprising: a reflective grid over the back surface, wherein thereflective grid comprises at least one reflective element, and the atleast one reflective element, the light absorption structure, and theconductive light reflection structure are arranged along a straightline.
 11. The image sensor device as claimed in claim 8, furthercomprising: a color filter over the back surface, wherein the colorfilter is over the light-sensing region; and a lens over the colorfilter.
 12. An image sensor device, comprising: a semiconductorsubstrate comprising a front surface, a back surface opposite to thefront surface, and a light-sensing region extending from the frontsurface into the semiconductor substrate; a conductive light reflectionstructure penetrating into the semiconductor substrate from the frontsurface, wherein the conductive light reflection structure is adjacentto the light-sensing region; a light absorption structure in thesemiconductor substrate and between the conductive light reflectionstructure and the back surface, wherein a first sidewall of theconductive light reflection structure and a second sidewall of the lightabsorption structure are substantially coplanar and connected to eachother, and a boundary is between the conductive light reflectionstructure and the light absorption structure and extends toward thelight-sensing region from a cross-sectional view of the conductive lightreflection structure, the light absorption structure, and thesemiconductor substrate; and an insulating layer in the semiconductorsubstrate and in direct contact with the first sidewall of theconductive light reflection structure and the second sidewall of thelight absorption structure to separate the conductive light reflectionstructure and the light absorption structure from the semiconductorsubstrate.
 13. The image sensor device as claimed in claim 12, wherein afirst top surface of the conductive light reflection structure, a secondtop surface of the insulating layer, and the front surface aresubstantially coplanar.
 14. The image sensor device as claimed in claim13, further comprising: a dielectric layer over the front surface,wherein the dielectric layer is in direct contact with the conductivelight reflection structure, the insulating layer, and the semiconductorsubstrate.
 15. The image sensor device as claimed in claim 12, whereinthe insulating layer is spaced apart from the back surface.
 16. Theimage sensor device as claimed in claim 12, further comprising: areflective grid over the back surface, wherein the reflective gridcomprises at least one reflective element, and the at least onereflective element, the light absorption structure, and the conductivelight reflection structure are aligned with each other.
 17. The imagesensor device as claimed in claim 12, wherein the back surface is moreclose to the boundary than the front surface.
 18. The image sensordevice as claimed in claim 12, wherein the conductive light reflectionstructure has a light reflectivity ranging from 60% to 100%, and thelight absorption structure has a light absorptivity ranging from 60% to100%.
 19. The image sensor device as claimed in claim 8, wherein thelight absorption structure is made of a polymer material.
 20. The imagesensor device as claimed in claim 6, wherein the conductive lightreflection structure and the light absorption structure are made ofdifferent materials.